The short version
- A Bayesian meta-analysis of 78 studies found only a trivial performance difference across the menstrual cycle, a median pooled effect size of -0.06, and graded the overall evidence quality as low.
- Those authors concluded that general guidelines on exercise performance across the cycle cannot be formed, and recommended a personalised approach based on each individual's own response.
- The evidence is thin because the question was barely asked: across 937 carbohydrate-fuelling studies, only about 11% of participants were women and roughly 69% did not report menstrual status.
- In a survey of 6,812 exercising women, 90.6% reported mood changes or anxiety and 86.2% reported fatigue, and higher symptom scores raised the odds of missing or changing training.
- A 2025 review of 31 randomised trials found consistent positive effects for vitamin B6, calcium and zinc on psychological PMS symptoms, and insufficient evidence for magnesium.
You have seen the wheel. Four coloured wedges, one per phase, each with an instruction: lift heavy here, do yoga here, eat more carbohydrate here, expect to feel unstoppable here. It is a beautiful piece of design. It is also considerably more confident than the literature it is drawn from.
We want to do two things in this article, and they only look contradictory. Tell you what the pooled evidence actually shows. And take your own experience of your cycle completely seriously, because those are separate questions with separate answers.
What the biggest meta-analysis found
The reference point here is McNulty and colleagues, 2020, in Sports Medicine: a systematic review and Bayesian meta-analysis of 78 studies, with 51 eligible for the pairwise analysis and 73 for a network meta-analysis comparing every cycle phase against every other.
The headline result is a trivial effect. Across both endurance and strength outcomes, performance was slightly reduced in the early follicular phase, with a median pooled effect size of -0.06 (95% credible interval -0.16 to 0.04) — an interval that includes zero. The largest single comparison, early follicular against late follicular, came in at -0.14 (95% CrI -0.26 to -0.03). The authors graded the overall quality of the evidence as "low" (42%).
Their own conclusion is worth reading twice: because of the trivial effect size, the large between-study variation and the number of poor-quality studies, general guidelines on exercise performance across the menstrual cycle cannot be formed. They recommend a personalised approach based on each individual's own response.
A 2023 umbrella review in Frontiers in Sports and Active Living looked specifically at resistance training and reached the same place from above: findings across published reviews were highly variable, methodological practices were poor and inconsistent, and in the authors' opinion it is premature to conclude that short-term fluctuations in reproductive hormones appreciably influence acute performance or longer-term strength and hypertrophy adaptations.
"Weak evidence" and "no effect" are not the same sentence
This is the part the debunkers get wrong in the other direction. The reason the evidence is thin is not that someone looked hard and found nothing. It is that the research was mostly not designed to answer the question.
The umbrella review above puts its finger on the reason: cycle phase is frequently not verified, and methodological practice across the literature is inconsistent enough that reviews of the same question keep landing in different places.
An audit published in Medicine & Science in Sports & Exercise in 2023 put numbers on it. Across 937 studies underpinning current carbohydrate-fuelling guidelines, with 11,202 participants, only about 11% of participants were women. Roughly 79% of studies used male-only cohorts. About 69% failed to provide sufficient information on participants' menstrual status. Of the 197 studies that did include women, 13 — around 7% — showed acceptable methodological control of ovarian hormones, and not one met all best-practice recommendations.
So when someone tells you the science says cycle phase doesn't matter for fuelling, the more accurate statement is that the science has barely asked.
Your symptoms are data. They are just different data.
Here is the study that keeps this article honest. Bruinvels and colleagues, 2021, in the British Journal of Sports Medicine, surveyed 6,812 exercising women across seven regions, recruited through the Strava user database. The most prevalent menstrual cycle symptoms were mood changes or anxiety (90.6%), tiredness or fatigue (86.2%), stomach cramps (84.2%) and breast pain or tenderness (83.1%).
After controlling for BMI, training volume and age, a higher symptom score was associated with greater odds of missing or changing training (OR 1.09), missing a competition (OR 1.07), and absenteeism from work or study (OR 1.08).
One disclosure, because you should have it: several of that paper's authors are employees or consultants of Orreco, which makes a cycle-tracking app. It doesn't invalidate a 6,812-person survey, but it is the kind of thing we would want told to us.
Put the two literatures side by side and the picture resolves. Lab-measured maximal performance appears to shift trivially across the cycle. Whether you turn up, how the session feels, and whether you finish it are affected a great deal. A meta-analysis of peak force output was never going to capture the second thing. It doesn't make it less real.
What about supplementing to the phase?
This is where we get to argue against our own shelf. A 2025 systematic review in Nutrition Reviews examined 31 randomised trials covering 3,254 participants on nutritional interventions for the psychological symptoms of premenstrual syndrome. Only one of the included studies was at low risk of bias, which tells you the state of the field.
Vitamin B6, calcium and zinc showed consistent significant positive effects. The review found insufficient evidence for vitamin B1, vitamin D, whole-grain carbohydrates, soy isoflavones, dietary fatty acids, multivitamin supplementation, PMS-specific diets — and magnesium.
LUVO sells magnesium. We do not sell B6, calcium or zinc. So on this specific use, the best current review does not support the product we make and does modestly support three we don't. We would rather you knew that from us.
What we'd actually tell you
Run your programme. Progressive overload, sleep, protein and consistency will outweigh cycle timing by an order of magnitude, and reorganising your training around a four-wedge infographic risks trading something that works for something that photographs well.
Then track for three cycles — session RPE, mood, sleep, cramps, whether you finished what you planned. If a pattern shows up in your log, act on it. That isn't us hedging; it is precisely what the meta-analysis authors recommended when the pooled data refused to give them a general rule.
You are allowed to move a heavy day. You just don't need permission from a wheel.
Good questions
Does cycle syncing your workouts actually work?
The pooled evidence does not support the four-wedge wheel. A Bayesian meta-analysis of 78 studies found a trivial difference in performance across the cycle, a median effect size of -0.06 with a credible interval crossing zero, and graded the evidence low quality. Its authors concluded that general guidelines cannot be formed and recommended a personalised approach instead. Run your programme; progressive overload and sleep outweigh cycle timing by an order of magnitude.
Should I lift heavy on my period?
If you feel like it, yes. The largest single phase comparison in the meta-analysis, early follicular against late follicular, came in at -0.14, small enough that it will be swamped by how much you slept and ate. You are allowed to move a heavy day when you feel awful. You just do not need permission from an infographic to do it.
If the research says the effect is trivial, why do I feel so much weaker some weeks?
Because the meta-analyses measured a different thing than the one you are experiencing. In 6,812 exercising women, 90.6% reported mood changes or anxiety and 86.2% reported tiredness, and higher symptom scores were associated with greater odds of missing or changing training. Lab-measured peak force shifts trivially. Whether you turn up and whether you finish the session is affected a great deal, and that never showed up in a force plate.
Does magnesium help with PMS?
Not according to the best current review, and we sell magnesium. A 2025 systematic review of 31 randomised trials in 3,254 participants found insufficient evidence for magnesium on the psychological symptoms of premenstrual syndrome, alongside vitamin D, soy isoflavones, multivitamins and several others. We would rather you heard that from us. If you take magnesium for something else, this does not change that case.
Are there any supplements with decent evidence for PMS mood symptoms?
Vitamin B6, calcium and zinc were the three that showed consistent significant positive effects in that 2025 review. We do not sell any of them. The same review noted that only one of its 31 included studies was at low risk of bias, which tells you the state of the field, so treat that as a direction worth discussing with a clinician rather than a settled answer.
How do I work out my own pattern?
Track three cycles. Log session RPE, mood, sleep, cramps, and whether you finished what you planned. If a pattern shows up in your own log, act on it. That is not us hedging: it is precisely what the meta-analysis authors recommended when the pooled data refused to give them a general rule that applied to everybody.
Sources
- McNulty KL, Elliott-Sale KJ, Dolan E, Swinton PA, Ansdell P, Goodall S, Thomas K, Hicks KM. The Effects of Menstrual Cycle Phase on Exercise Performance in Eumenorrheic Women: A Systematic Review and Meta-Analysis. Sports Med, 2020. View study
- Colenso-Semple LM, D'Souza AC, Elliott-Sale KJ, Phillips SM. Current evidence shows no influence of women's menstrual cycle phase on acute strength performance or adaptations to resistance exercise training. Front Sports Act Living, 2023. View study
- Bruinvels G, Goldsmith E, Blagrove R, et al. Prevalence and frequency of menstrual cycle symptoms are associated with availability to train and compete: a study of 6812 exercising women recruited using the Strava exercise app. Br J Sports Med, 2021. View study
- Kuikman MA, Smith ES, McKay AKA, et al. Fueling the Female Athlete: Auditing Her Representation in Studies of Acute Carbohydrate Intake for Exercise. Med Sci Sports Exerc, 2023. View study
- Robinson J, Ferreira A, Iacovou M, Kellow NJ. Effect of nutritional interventions on the psychological symptoms of premenstrual syndrome in women of reproductive age: a systematic review of randomized controlled trials. Nutr Rev, 2025. View study
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